Beam compass



0d. 19,l 1943. H, L, DE USLE 2,331,892 v BEAM COMPASS Filed Jlglly 14, 1941 Patented Oct. 19, 1943 UNI-TED STATES Para Nr HaroldL. De-.LisleShehoygan, Wim; Viilliarny ifi, Murphy, executor of said HaroldA L.,De Lisle,

'deceased Application July-I4', 1941, SREiaLNQZQ-M 1. k(Cl. :i3-158)v This invention rela-testo beamy Compasses andv aims to' provide Aan improved? consti-Auction thereof which permits greater compactness withenhanced utilityiorsuohfa device;A

Other objects and advantages willi be apparentV from the following# description, taken together withV the accompanying-drawing, in which- Figurev 1: is apl'amview', partially-insomnio, of

abeam-v compass constructed in accordance with ance with thefpresent.V invention, lll-1 and i if are-A a pair of spring steel tapes ci3 the-kindpurchasea le on tliegmarket and'iw'hich have-Ya.- naturally arcuate cross-section, yas indicated*atA |12. It `will be understood thatI suchy tapes maybe wound somewhat as on a reelI andi that i-n-such winding the tapes are flattened out-soas to occupy a? minimum of space,- the flattening-permittingthe winding. in this instanee-theftapes: l0 and li area continuous tape having twov runsor, in vother- Words, are continuousancllintegral aty oneY endl of each and together comprise a beam for the compass, the beam being V-extensilille and retractible, as presently morev particularly described.

One end oi the tape l may be anchored in a, slot I3 as by pins i4 in a box l5 which is conveniently formed of Wood or, say, of a molded plastic material. A filler l5 forced into the slot IS with the end of the tape I serves to effect a tight nt for the tape in the slot. The tape lil passing in the other direction enters a slot I1 in another box i3, and passes through a semicircular groove I9 therein as at 2D to emerge through another slot 2i in the box I8 as an integral continuation, in this instance, of the second tape Il. The second tape H passes back into the first box i5 as through a slot 22 and into a cylindrical chamber 23 therein where it winds upon itself as at 24, having a free end 25 within the chamber at the innermost of the windings 24. Thus arranged the slots 2l and 22 in the boxes 'i8 and l5 respectively are tangential to the tape convolutions 20 and 24, and are elongated in the direction of the tape passing through the slots CIK spring normallyl biases the.y sections 26 'and 2li and? v'Ilie-siotsL boxes serve" tio-assistin flattening the tapes;

It will be understood that the boxes; asibe'st showniin Figs. 2; Svandl; may be advantageously v split" perpendicular to the5 axesoitlie-boxes'andi thusoonstructed infmating half-sections.-

The box' le comprises afpairci in aT-halte sections; 26: andn', the-'slots' Hf andlt being formed half? in each ci these mating-11sections;

which are releasably clamped together asffliy-ai thu-mb'fscrew- 2@v passing through these'ction 26 tionl 27.'. About the shan-lr @ifA the thnmbescrevr 2v8li`s ldesiraiol'y a compressionv coil springry 'Tly infal counterborevl inthe-boxsection 2.5;wh

apart, so thatlvthey are. forcedi together-fbysitlie;t thumbescrew- 2S against the-resilience oil the: spring'vSD. j

Similarly, the box Mr-may be'forrnedloimatlng sections and; the: slots: lit andfzfbeirig similarly iormedihalif inieachisection. Thev boni..

I 5 1 may similarly-- have ai thLnnh-screvv' "-.vvh passes centrally through theseetions 324 an which arefY centrally` interiorlyft Yh'ulob'eda asti: atY .'s' andfit.l (Fig 42) within'the .Chambon 3l. serves: the. same'function1 in: this@ box'f Ilftlrati the springfs'ilserves-irrzthe box'. H

Onef ofthe-sectionsc'of each..l box, in: tins-aimv` stance the. section ci thesbox Iitf'ancl'@tltierjse'c;V tion; 33'- of` theA boxrl 5,;i'smoderati-tas; at't33sand'i39f;

respectively.' to` .permit the otherfrsectiorn to bei extended.. In the .case offthef box:t3;;.the:seetion" 2 'l:isrthus-extendedias at-:4'lL-to have'fsecured tl'fereto a plate 4I as by screws 42 for mounting an instrument such as the needle-point leg 43. Similarly the section 32 is extended as at 44 to have secured thereto a plate 45 as by screws 46 for mounting a drawing instrumentgor, in this case, pencil leg 41. The extensions 40 and 44 also provide offset interengaging portions with the undercuts 33 and 39 respectively to prevent relative rotation of the mating sections of the boxes respectively by reason of Vthe shoulders thus provided where the meeting plane of the sections is offset. i

The pencil leg 4'! may be the usual type purchasable on the market and pivoted as at 48, having an arm 49 through which passes a post 5U on which the arm 4S may be moved as by a thumbscrew 5| against the force of a spring'52 to perpencil leg 4l'.

It will be understood that the principal adjustment for the length of the beam compass is afspringi forded, following the present disclosure, by iirst slightly unscrewing the thumb-screws 28 and 34 so as to release the tapes in the boxes and then pulling the boxes apart, the tapes unwinding therefrom as the boxes are moved apart, to the desired principal distance adjustment. Thereupon, the screws 28 and 34 are again tightened to fix the distance ofV projection of the tapes from the boxes. Because of the inherent characteristics of the tapes as beams by their arcuate crosssection, the structure is rigid for the purpose here referred to.

When the device has served its purpose for the time, the thumb-screws 23 and 34 may be released and the boxes pushedV together again, at which time the tapes will be windingly received in the boxes and the thumb-screws again tightened to maintain the boxes together. poses of such mating, the boxes desirably have ilat faces 53 and 54 along their adjacent sides, while their outer sides are appropriately rounded as at 55 and 5t to form a composite whole of pleasing appearance.

Guide pins 62 in some of the mating sections of the boxes received in recesses G3 in the opposite sections x the bo-x sections against rotative displacement while permitting some movement toward and from each other under the iniluence of the springs 353 and 3l and thumb-screws 23 and 34.

Thus, I make a novel use of the rigidity and yet windability of a steel tape of this type to act as a beam for an improved beam compass, one end of the tape carrying a drawing instrument and the other end a box or housing for changing the direction of the tape. spring is required to retract the tape since the tape is not limp but is highly resilient and maintains itself against the vvail` 23 of the interior chamber of the box i; the free end 25 ofthe tape being urged by its vown resilience toward this wall without any extraneous means for this purpose and yielding only to accommodate the winding of the tape upon itself as the tape is retracted and more conVolutio-ns of the tape are received within the box. Conversely, as the tape is extended and fewer convolutions remain in the box, the iree end 25 is still urged by its own For pur- It will be seen that no ment here shown, since the arrangement makes use for this purpose of the friction or braking action resulting when the arcuation of the tape outside of the box I5 disappears as the tape is retracted into the box and its cross-section becomes flat as in the convolutions 24. This change, as shown in Figs. 1 and 3, from an arcuate to a ilat cross-section takes placein the slot 22 and where thisl slot mergesinto the chamber 23. Consequently in practice suilicient friction or braking action is thus provided so that only a minimum use of the thumb-screw 34 is necessary, and the thumb-screw 34 is not for the purpose of producing greater friction but rather so that less friction may occur in order to make it easier to push the tape into the box or to pull it therefrom, the tightening of the thumb-screw 34 being usually done when the tape is extended or retracted to nearly its fullest extent and then only as an auxiliary means supplementing the inherent braking action of the improved device.

Having described my invention, I claim:

In a beam compass comprising an extensible and retractible spring metal normally transversely arcuate tape received at one end in a box therefor and extending between relatively movable parts of the compass, that improvement therein in which the box is split perpendicularly to its axis whereby it is constructed in mating sections and has a cylindrical chamber having a plain wall therein formed jointly by said mating sections receiving a free unconnected end of the tape in convolutions of flattened cross-section, the natural resilience of the tape urging said free end toward the Vwall of said chamber and said free end moving toward or from said wall as the tape is extended or retracted and the number of convolutions in the chamber is diminished or increased, the box having a tangential slot therein materially elongated in the longitudinal direction of the tape for the passage o-f the tape from said chamber and the tape where passing therethrough changing from an arcuate to a flattened cross-section whereby friction is produced which restrains outward movement of the tape unless positively actuated, and in which a thumb-screw passes through the mating sections centrally 0I" said chamber to retain said mating sections adjustably together and offset interengaging portions are provided on the mating sections to prevent relative rotation of said sections, one of said olset portions providing securing means for a compass part.

HAROLD L. DE LISLE. 

